Nanocomposite materials have been the subject of much academic and industrial literature due to a large extent on their ability to impart new properties for a given material. In particular, polymeric nanocomposites, such as elastomer-clay nanocomposites, have been of considerable interest. As used here, nanocomposites or polymeric nanocomposites are typically polymer systems containing inorganic particles with at least one dimension in the nanometer range of the polymer matrix.
The preparation of nanocomposites uses a number of methods to generate exfoliated clays. One of the most common methods relies upon the use of organically modified montmorillonite clays. Organoclays are typically produced through solution based ion-exchange reactions that replace sodium ions that exist on the surface of sodium montmorillonite with organic molecules such as alkyl or aryl ammonium compounds and typically known in the industry as swelling or exfoliating agents. See, e.g., U.S. Pat. No. 5,807,629, WO 02/100935, and WO 02/100936. Other background references include U.S. Pat. Nos. 5,576,373, 5,665,183, 5,807,629, 5,936,023, 6,121,361, WO 94/22680, WO 01/85831, and WO 04/058874.
However, the alkyl chain length/type of many ammonium compounds limits the separation as shown, for example, in d-spacing between layers and the compatibility between the alkyl chains and polymer backbone. Therefore, new exfoliating agents are needed for improvements to modified layer fillers to produce nanocomposite compositions with improved properties such as better barrier properties for innerliner applications.